Answer:
-2000 J (heat lost)
Explanation:
We can solve the problem by using the 1st law of thermodynamics:
[tex]\Delta U = Q-W[/tex]
where
[tex]\Delta U[/tex] is the change in internal energy of a system
Q is the heat absorbed by the system
W is the work done by the system
In this situation, we have
[tex]W=1000 W[/tex] (work done by the student)
[tex]\Delta U = -3000 J[/tex] (decrease in internal energy)
So the heat is
[tex]Q=\Delta U + W = -3000 J +1000 J = -2000 J[/tex]
And the negative sign means the student has lost heat.
